The development of novel and effective treatments for cancer requires a fundamental understanding of how regulatory proteins switch on and off gene expression patterns that mediate cell growth, neoplasia, metastasis, angiogenesis, etc. in human cells. A comprehensive understanding of the function and structure of multi-subunit transcription complexes responsible for directing the vast networks of regulatory signals controlling gene expression in humans poses a formidable challenge that forms the basis of this grant proposal. To tackle the difficult structure/function problems inherent with studying multi-subunit transcription complexes, we propose to launch a coordinated and interdisciplinary effort to determine the 3D structures of key multi-subunit transcription complexes and unravel the mechanisms that regulate gene transcription in human and animal cells. A key aspect of this P01 Program Project Grant will be to establish highly interactive collaborations across disciplines and research institutes to study the structure/function relationships of large multi-subunit transcription complexes. By combining the expertise of several investigators, we propose to implement a battery of complementary biochemical and biophysical methods including: Project 1, electron microscopy and single particle reconstruction of activator/co-activator complexes as well as chromatin remodeling activities;Project 2, biochemistry of protein:protein interactions and X-ray crystallography of large multi-subunit transcription complexes (TFIIA and TFIID);and Project 3, single molecule FRET analysis of the dynamic assembly of transcription components with DNA and promoter elements. A major component of this proposal will be the establishment of a biochemistry and core protein laboratory to serve as the nerve center and clearinghouse for generating the many cell lines, expression clones, protein complexes, and purification strategies to be used by each of the three Research Projects. Thus, our goal is to develop a highly synergistic and concerted effort to carry out a pioneering set of interdependent experiments by using the same molecular reagents but applying distinct and complementary research strategies to dissect the core machinery responsible for gene control leading to cancer.